Catalyst composition

ABSTRACT

A catalyst composition for polymerization of a conjugated diene or copolymerization of a conjugated diene and an aromatic vinyl compound, which comprises the following components: (A) a metallocene-type complex of a rare earth metal compound (samarium complex etc.), and (B) an ionic compound composed of a non-coordinate anion and a cation (triphenylcarbonium tetrakis(pentafluorophenyl) borate etc.) and/or an aluminoxane. The catalyst composition producing a polymer having a high cis-1,4-configuration content in the microstructure and a narrow molecular weight distribution.

TECHNICAL FIELD

The present invention relates to a catalyst composition forpolymerization of a conjugated diene and a co-catalyst contained in thecatalyst composition. The invention also relates to a method forpreparing a conjugated diene polymer using the catalyst composition anda novel conjugated diene polymer obtained by the preparation method.

The present invention further relates a catalyst composition for thecopolymerization of a conjugated diene and an aromatic vinyl compoundand a co-catalyst contained in the catalyst composition. The inventionalso relates to a method for preparing a copolymer of a conjugated dieneand an aromatic vinyl compound using the catalyst composition and anovel copolymer obtained by the preparation method.

BACKGROUND ART

Various proposals have been made so far as to polymerization catalystsfor conjugated dienes, and they play a highly important role inindustrial fields. In particular, various polymerization catalysts whichgive a high cis-1,4-linkage content have been studied and developed toobtain conjugated diene polymers with enhanced performance in thermaland mechanical properties. For example, complex catalyst systemscontaining a compound of a transition metal such as nickel, cobalt andtitanium as a main component are known, and some of them have alreadybeen widely used in industrial applications as polymerization catalystsfor butadiene, isoprene etc. (see, End. Ing. Chem., 48, 784, 1956;Japanese Patent Publication No. 37-8198).

In order to attain a higher cis-1,4-linkage content and superiorpolymerization activity, complex catalyst systems which consist of arare earth metal compound and an organometallic compound belonging toGroup I to Group III have been studied and developed, and highlystereospecific polymerization has come to be actively studied (Makromol.Chem. Suppl, 4, 61, 1981; J. Polym. Sci., Polym. Chem. Ed., 18, 3345,1980; German Patent Application No. 2,848,964; Sci. Sinica., 2/3, 734,1980; Rubber Chem. Technol., 58, 117, 1985 etc.). Among these catalystsystems, complex catalysts containing a neodymium compound and anorganoaluminum compound as main components were revealed to give a highcis-1,4-linkage content and have superior polymerization activity. Thecatalysts have already been used in industrial applications aspolymerization catalysts for butadiene etc. (see Macromolecules, 15,230, 1982; Makromol. Chem., 94, 119, 1981).

With the recent progress of industrial technologies, requirements forpolymeric materials as commercial products have become increasinglyhigher, and development of polymeric materials which have still higherthermal properties (thermal stability etc.) and mechanical properties(tensile modulus, bending modulus etc.) has come to be strongly desired.As one of promising means for achieving the object, there have beenattempts to produce a polymer of a high cis-1,4-configuration content inmicrostructure and a narrow molecular weight distribution by using acatalyst having a high polymerization activity for conjugated dienes.However, no method has so far been found for producing polymers havingsuch characteristics.

Further, various proposals have hitherto been made also as to catalystsfor copolymerization of a conjugated diene and an aromatic vinylcompound, and they play an extremely important industrial role. Inparticular, various copolymerization catalysts which give a highcis-1,4-linkage content have been studied and developed to obtaincopolymers of a conjugated diene and an aromatic vinyl compound withenhanced performance in thermal and mechanical properties.

For example, there are known complex catalyst systems containing acompound of transition metal such as nickel, cobalt and titanium (seeKogyo Kagaku Zasshi (Journal of Industrial Chemistry), 72, 2081, 1969;Plast. Kautsch., 40, 356, 1993; Makromol. Chem. Phys., 195, 2623, 199etc.), complex catalyst systems containing a compound of rare earthmetal such as neodymium and gadolinium (Macromol. Rapid Commun. 16, 563,1992; J. Polym. Sci., ParA; Polym. Chem., 32, 1195, 1994; Polymer, 37,349, 1996) and the like. Although these catalyst systems exhibit arelatively high cis-1,4-controllability, polymers with a high molecularweight and narrow molecular weight distribution, and copolymers withrandomized monomer sequence cannot be obtained by means of thesecatalysts.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a catalyst for thepolymerization of a conjugated diene. More specifically, the object isto provide a catalyst for producing polymers with a highcis-1,4-configuration content in the microstructure and a narrowmolecular weight distribution. Another object of the present inventionis to provide polymers having the aforementioned characteristics, and amethod for producing such polymers.

Further object of the present invention is to provide a catalyst forcopolymerization of a conjugated diene and an aromatic vinyl compound.More specifically, the object is to provide a catalyst for producingcopolymers with high cis-1,4-configuration content in themicrostructure, a high molecular weight and a narrow molecular weightdistribution. Another object of the present invention is to providecopolymers having the aforementioned characteristics, and a method forproducing such copolymers.

The inventors of the present invention conducted various studies toachieve the foregoing objects. As a result, they found that a conjugateddiene can be efficiently polymerized by using a catalyst compositioncomprising a rare earth metal metallocene type polymerization catalystand a co-catalyst comprising an ionic compound composed of anon-coordinate anion and a cation and/or an aluminoxane in combination,and that a conjugated diene polymer with an extremely highcis-1,4-configuration content in the microstructure and a narrowmolecular weight distribution can be produced by using theaforementioned catalyst composition for polymerization.

Moreover, the inventors of the present invention also found that aconjugated diene and an aromatic vinyl compound can be efficientlycopolymerized by using a catalyst composition comprising a rare earthmetal metallocene-type polymerization catalyst and a co-catalystcontaining an ionic compound composed of a non-coordinate anion and acation and/or an aluminoxane in combination, and that, by using theaforementioned catalyst composition for copolymerization, a copolymerwith an extremely high cis-1,4-configuration content in themicrostructure as well as a high molecular weight and a narrow molecularweight distribution, preferably a random copolymer with a randomizedmonomer sequence, can be produced by copolymerizing a conjugated dieneand an aromatic vinyl compound. The present invention was achieved onthe basis of these findings.

The present invention thus provides a catalyst composition forpolymerization of a conjugated diene, which comprises the followingcomponents: (A) a metallocene type complex of a rare earth metalcompound, and (B) an ionic compound composed of a non-coordinate anionand a cation and/or an aluminoxane. According to preferred embodimentsof the present invention, there are provided the aforementioned catalystcomposition, wherein the metallocene type complex is a samarium complex;the aforementioned catalyst composition, wherein the ionic compound istriphenylcarbonium tetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis-(tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate or 1,1′-dimethylferroceniumtetrakis(pentafluorophenyl)borate; and the aforementioned catalystcomposition, which further contains an organometallic compound of anelement belonging to Group I to Group III in the periodic table.

According to a further aspect of the present invention, there isprovided a co-catalyst for use in combination with a catalyst containinga metallocene type complex of a rare earth metal compound forpolymerization of a conjugated diene, which comprises an ionic compoundcomposed of a non-coordinate anion and a cation and/or an aluminoxane.According to further aspects of the present invention, there areprovided a method for polymerization of a conjugated diene wherein thepolymerization is performed in the presence of the aforementionedcatalyst composition for polymerization; and a polymer which isobtainable by polymerization of a conjugated diene in the presence ofthe aforementioned catalyst composition for polymerization. In addition,there is also provided a polymer wherein a cis-1,4-configuration contentin the microstructure is 80 mol % or more, preferably 90 mol % or more,further preferably 95 mol % or more, and most preferably 98 mol % ormore, and a molecular weight distribution Mw/Mn is 2.00 or less,preferably 1.80 or less, more preferably 1.60 or less, furtherpreferably 1.40 or less, and most preferably 1.30 or less. The abovepolymer can be produced by polymerizing a conjugated diene in thepresence of the aforementioned catalyst composition for polymerization.

According to a further aspect of the present invention, there isprovided a catalyst composition for copolymerization of a conjugateddiene and an aromatic vinyl compound, which contains the followingcomponents: (A) a metallocene type complex of a rare earth metalcompound, and (B) an ionic compound composed of a non-coordinate anionand a cation and/or an aluminoxane. According to preferred embodimentsof the present invention, there are provided the aforementioned catalystcomposition, wherein the metallocene type complex is a samarium complex;the aforementioned catalyst composition, wherein the ionic compound istriphenylcarbonium tetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis-(tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate or 1,1′-dimethylferroceniumtetrakis(pentafluorophenyl)borate; and the aforementioned catalystcomposition, which further contains an organometallic compound of anelement belonging to Group I to Group III in the periodic table.

According to a further aspect of the present invention, there areprovided a co-catalyst for use in combination with a catalyst containinga metallocene type complex of a rare earth metal compound forcopolymerization of a conjugated diene and an aromatic vinyl compound,which comprises an ionic compound composed of a non-coordinate anion anda cation and/or an aluminoxane. According to further aspects of thepresent invention, there are provided a method for copolymerization of aconjugated diene and an aromatic vinyl compound wherein thecopolymerization is performed in the presence of the aforementionedcatalyst composition for polymerization; and a copolymer which can beobtained by copolymerization of a conjugated diene and an aromatic vinylcompound in the presence of the aforementioned catalyst composition.

In addition, there is also provided a copolymer wherein acis-1,4-configuration content in the microstructure is 80 mol % or more,preferably 90 mol % or more, and most preferably 95 mol % or more; amolecular weight Mn is 10,000 or more, preferably 20,000 or more,further preferably 50,000 or more, and most preferably 100,000 or more,and a molecular weight distribution Mw/Mn is 2.50 or less, preferably2.00 or less, more preferably 1.80 or less, and most preferably 1.50 orless. This copolymer can be produced by copolymerizing a conjugateddiene and an aromatic vinyl compound in the presence of theaforementioned catalyst composition for copolymerization.

BEST MODE FOR CARRYING OUT THE INVENTION

Examples of the metallocene type complex of a rare earth metal compoundinclude divalent or trivalent rare earth metal compounds represented bythe general formula (I): R_(a)MX_(b). L_(c) or the general formula (II):R_(a)MX_(b)QX_(b) wherein M represents a rare earth metal; R representscyclopentadienyl group, a substituted cyclopentadienyl group, indenylgroup, a substituted indenyl group, fluorenyl group, or a substitutedfluorenyl group; X represents hydrogen atom, a halogen atom, an alkoxidegroup, a thiolate group, an amido group, or a hydrocarbon group having 1to 20 carbon atoms; L represents a Lewis base compound; Q represents anelement belonging to Group III in the periodic table; a represents aninteger of 1, 2 or 3; b represents an integer of 0, 1 or 2; and crepresents an integer of 0, 1 or 2.

In the aforementioned general formula (I), an element selected fromthose of atomic numbers 57 to 71 in the periodic table can be used asthe rare earth metal represented by M. Specific examples of the rareearth metal include lanthanium, cerium, praseodymium, neodymium,promethium, samarium, europium, gadolinium, terbium, dysprosium,holmium, erbium, thulium, ytterbium and lutetium. Among them, samariumis preferred. When the symbol “a” is 2, two of“R” may be the same ordifferent from each other. Similarly, when the symbol “b” or “c” is 2,two of “X” or “L” may be the same or different from each other.

The types, numbers, and substituting positions of one or moresubstituent of the substituted cyclopentadienyl group, substitutedindenyl group, and substituted fluorenyl group are not particularlylimited. Examples of the substituent include, for example, methyl group,ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutylgroup, sec-butyl group, tert-butyl group, hexyl group, phenyl group andbenzyl group, as well as hydrocarbon groups containing a silicon atomsuch as trimethylsilyl group. R may be bound to a part of X by means ofa bridging group such as dimethylsilyl group, dimethylmethylene group,methylphenylmethylene group, diphenylmethylene group, ethylene group,and substituted ethylene group, and two of R may be bound to each otherby means of a bridging group such as dimethylsilyl group,dimethylmethylene group, methylphenylmethylene group, diphenylmethylenegroup, ethylene group, and substituted ethylene group.

Specific examples of the substituted cyclopentadienyl group include, forexample, methylcyclopentadienyl group, benzylcyclopentadienyl group,vinylcyclopentadienyl group, 2-methoxyethylcyclopentadienyl group,trimethylsilycyclopentadienyl group, tert-butylcyclopentadienyl group,ethylcyclopentadienyl group, phenyl-cyclopentadienyl group,1,2-dimethylcyclopentadienyl group, 1,3-dimethylcyclopentadienyl group,1,3-di(tert-butyl)cyclopentadienyl group,1,2,3-trimethylcyclopentadienyl group,1,2,3,4-tetramethylcyclopentadienyl group, pentamethylcyclopentadienylgroup, 1-ethyl-2,3,4,5-tetramethylcyclopentadienyl group,1-benzyl-2,3,4,5-tetramethylcyclopentadienyl group,1-phenyl-2,3,4,5-tetramethylcyclopentadienyl group,1-trimethylsilyl-2,3,4,5-tetramethylcyclopentadienyl group,1-trifluoromethyl-2,3,4,5-tetramethylcyclopentadienyl group and thelike. Specific examples of the substituted indenyl group include, forexample, 1,2,3-trimethylindenyl group, heptamethylindenyl group,1,2,4,5,6,7-hexamethylindenyl group and the like.Pentamethylcyclopentadienyl group is preferred as R.

The alkoxide group represented by X may be any of aliphatic alkoxygroups such as methoxy group, ethoxy group, propoxy group, n-butoxygroup, isobutoxy group, sec-butoxy group and tert-butoxy group, and aryloxide groups such as phenoxy group, 2,6-di-tert-butylphenoxy group,2,6-diisopropylphenoxy group, 2,6-dineopentylphenoxy group,2-tert-butyl-6-isopropylphenoxy group, 2-tert-butyl-6-neopentylphenoxygroup and 2-isopropyl-6-neopentylphenoxy group. A preferred exampleincludes 2,6-di-tert-butylphenoxy group.

The thiolate group represented by X may be any of aliphatic thiolategroups such as thiomethoxy group, thioethoxy group, thiopropoxy group,thio-n-butoxy group, thioisobutoxy group, thio-sec-butoxy group,thio-tert-butoxy group, and aryl thiolate groups such as thiophenoxygroup, 2,6-di-tert-butylthiophenoxy group, 2,6-diisopropylthiophenoxygroup, 2,6-dineopentylthiophenoxy group,2-tert-butyl-6-isopropylthiophenoxy group,2-tert-butyl-6-thioneopentylphenoxy group,2-isopropyl-6-thioneopentylphenoxy group and2,4,6-triisopropylthiophenoxy group. A preferred example includes2,4,6-triisopropylthiophenoxy group.

The amido group may be any of aliphatic amido groups such asdimethylamido group, diethylamido group and diisopropylamido group, andarylamido groups such as phenylamido group, 2,6-di-tert-butylphenylamidogroup, 2,6-diisopropylphenylamido group, 2,6-dineopentylphenylamidogroup, 2-tert-butyl-6-isopropylphenylamido group,2-tert-butyl-6-neopentylphenylamido group,2-isopropyl-6-neopentylphenylamido group and 2,4,6-tert-butylphenylamidogroup. A preferred example includes 2,4,6-tert-butylphenylamido group.

The halogen atom represented by X may be any of fluorine atom, chlorineatom, bromine atom, and iodine atom. Chlorine atom and iodine atom arepreferred. Specific examples of the hydrocarbon group having 1 to 20 ofcarbon atoms include, for example, linear or branched aliphatichydrocarbon groups such as methyl group, ethyl group, n-propyl group,isopropyl group, n-butyl group, isobutyl group, sec-butyl group,tert-butyl group, neopentyl group, hexyl group and octyl group, aromatichydrocarbon groups such as phenyl group, tolyl group and naphthyl group,and aralkyl groups such as benzyl group, as well as hydrocarbon groupscontaining a silicon atom such as trimethylsilylmethyl group andbistrimethylsilylmethyl group. Among them, methyl group, ethyl group,isobutyl group, trimethylsilylmethyl group and the like are preferred.As X, hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to20 carbon atoms is preferred.

The Lewis base compound represented by L is not particularly limited solong as said compound can coordinate to a metal by means of an electronpair, and the compound may be an inorganic compound or an organiccompound. Examples of the Lewis base compound include ether compounds,ester compounds, ketone compounds, amine compounds, phosphine compounds,silyloxy compounds and the like. However, the compounds are not limitedto the above examples. In the general formula (II), Q represents anelement belonging to Group III in the periodic table. Examples of suchan element are boron, aluminum, gallium and the like. Aluminum ispreferred.

Specific examples of the metallocene type complex of a rare earth metalcompound represented by the formula (I) include, for example,bispentamethylcyclopentadienylbistetrahydrofuran samarium,methylbispentamethylcyclopentadienyltetrahydrofuran samarium,chlorobispentamethylcyclopentadienyltetrahydrofuran samarium,iodobispentamethylcyclopentadienyltetrahydrofuran samarium and the like.Examples of the metallocene type complex of a rare earth metal compoundrepresented by the formula (II) include, for example,dimethylaluminum(μ-dimethyl)bis(pentamethylcyclopentadienyl) samariumand the like.

The ionic compound used as a co-catalyst is not particularly limited solong as the compound is composed of a non-coordinate anion and a cation.Examples include, for example, ionic compounds that can react with theaforementioned rare earth metal compounds to generate a cationictransition metal compound. Examples of the non-coordinate anion include,for example, tetra(phenyl)borate, tetrakis(monofluorophenyl)borate,tetrakis(difluorophenyl)borate, tetrakis(trifluorophenyl)borate,tetrakis(trifluorophenyl)borate, tetrakis(pentafluorophenyl)borate,tetrakis(tetrafluoromethylphenyl)borate, tetra(tolyl)borate,tetra(xylyl)borate, (triphenylpentafluorophenyl)borate,[tris(pentafluorophenyl), phenyl]borate,tridecahydride-7,8-dicarbaundecaborate and the like.

Examples of the cation include, for example, carbon cations, oxoniumcations, ammonium cations, phosphonium cations, cycloheptatrienylcations, ferrocenium cations that contain a transition metal and thelike. Specific examples of the carbonium cations include trisubstitutedcarbonium cations such as triphenylcarbonium cation and trisubstitutedphenylcarbonium cations. Specific examples of the trisubstitutedphenylcarbonium cations include tri(methylphenyl)carbonium cation,tri(dimethylphenyl)carbonium cation and the like. Specific examples ofthe ammonium cations include trialkylammonium cations such astrimethylammonium cation, triethylammonium cation, tripropylammoniumcation, tributylammonium cation and tri(n-butyl)ammonium cation,N,N-dialkylanilinium cations such as N,N-diethylanilinium cation andN,N-2,4,6-pentamethylanilinium cation, dialkylammonium cations such asdi(isopropyl)ammonium cation and dicyclohexylammonium cation and thelike. Specific examples of the phosphonium cations includetriarylphosphonium cations such as triphenylphosphonium cation,tri(methylphenyl)phosphonium cation and tri(dimethylphenyl)phosphoniumcation.

Preferably used ionic compounds are those consisting of components incombination each of which is arbitrarily selected from thenon-coordinate anion and the cation. Preferred examples of the ioniccompound are, for example, triphenylcarboniumtetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis(tetrafluorophenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, 1,1′-dimethylferroceniumtetrakis(pentafluorophenyl)borate and the like. The ionic compounds maybe used alone, or two or more of them may be used in combination. As aLewis acid that can react with a transition metal compound to generate acationic transition metal compound, B(C₆F₅)₃, Al(C₆F₅)₃ and the like maybe used, and these acids may be used in combination with theaforementioned ionic compounds.

As the aluminoxane used as the co-catalyst, for example, those obtainedby contacting an organoaluminum compound with a condensing agent can beused. More specifically, linear aluminoxanes and cyclic aluminoxanesrepresented by the general formula (—Al(R′)O—)_(n) can be used. In theformula, R′ is a hydrocarbon group having 1 to 10 carbon atoms, and thishydrocarbon group may be substituted with a halogen atom and/or analkoxy group. The symbol “n” represents degree of polymerization, and“n” is preferably 5 or more, more preferably 10 or more. Examples of R′include methyl group, ethyl group, propyl group, isobutyl group and thelike, and methyl group is preferred. Examples of the organoaluminumcompound used as a raw material of the aluminoxane include, for example,trialkylaluminum such as trimethylaluminum, triethylaluminum andtruiisobutylaluminum, mixtures thereof and the like, andtrimethylaluminum is especially preferred. Aluminoxanes produced byusing a mixture of trimethylaluminum and tributylaluminium as a rawmaterial can also be suitably used. The aluminoxanes may be used incombination with the ionic compounds.

The catalyst composition of the present invention contains theaforementioned components (A) and (B), and may further contain anorganometallic compound of an element belonging to Groups I to III inthe periodic table as a component (C). Examples of the organometalliccompound include organic aluminum compounds, organic lithium compounds,organic magnesium compounds, organic zinc compounds, organic boroncompounds and the like. More specifically, methyllithium, butyllithium,phenyllithium, benzyllithium, neopentyllithium,trimethylsilylmethyllithium, bistrimethylsilylmethyllithium,dibutylmagnesium, dihexylmagnesium, diethylzinc, dimethylzinc,trimethylaluminum, triethylaluminum, triisobutylaluminium,trihexylaluminium, trioctylaluminium, tridecylaluminium and the like maybe used. Furthermore, organic metal halide compounds such asethylmagnesium chloride, butylmagnesium chloride, dimethylaluminumchloride, diethylaluminum chloride, sesquiethylaluminum chloride andethylaluminium dichloride, and hydrogenated organometallic compoundssuch as diethylaluminum hydride and sesquiethylaluminum hydride may beused. These organometallic compounds may be used alone, or two or moreof them may be used in combination.

The mixing ratio of the aforementioned components (A) and (B) in thecatalyst composition of the present invention may be suitably selecteddepending on the type of a monomer used for polymerization, the type andconditions of a reaction and the like. In a composition containing arare earth metal compound and an aluminoxane, the ratio of the component(A) and the component (B) (molar ratio) is generally about 1:1 to1:10000, preferably 1:10 to 1:1000, and more preferably 1:50 to 1:500.In a composition containing a rare earth metal compound and an ioniccompound, the ratio of the component (A) and the component (B) (molarratio) may be about 1:0.1 to 1:10, preferably 1:0.2 to 1:5, and morepreferably 1:0.5 to 1:2. In a composition containing the component (C),the mixing ratio of the rare earth metal compound and the component (C)(molar ratio) may be, for example, about 1:0.1 to 1:1000, preferably1:0.2 to 1:500, and more preferably 1:0.5 to 1:50.

The type of the conjugated diene compound as a monomer that can bepolymerized by the polymerization method of present invention is notparticularly limited. Examples of the monomer include, for example,1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene,2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene,2,4-hexadiene or the like. Among them, 1,3-butadiene is preferred. Thesemonomer components may be used alone, or two or more of them may be usedin combination.

The type of the conjugated diene compound as a monomer that can becopolymerized by the polymerization method of present invention is notparticularly limited. Examples of the monomer include, for example,1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene,2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene,2,4-hexadiene or the like. Among them, 1,3-butadiene is preferred. Thesemonomer components may be used alone, or two or more of them may be usedin combination.

The type of the aromatic vinyl compound monomer that can becopolymerized by the polymerization method of present invention is notalso particularly limited, and it may be, for example, styrene,p-methylstyrene, m-methylstyrene, p-tert-butyl-styrene, α-methylstyrene,chloromethylstyrene, p-tert-butoxystyrene, dimethylaminomethylstyrene,dimethylaminoethylstyrene, vinyltoluene or the like. Among them, styreneis preferred. These monomer components may be used alone, or two or moreof them may be used in combination.

The polymerization method of the present invention may be performedeither in the presence or absence of a solvent. Where a solvent is used,the kind of the solvent is not particularly limited so long as thesolvent is substantially inactive in the polymerization reaction and hassufficient solubility for the monomer and the catalyst composition.Examples of the solvent include, for example, saturated aliphatichydrocarbons such as butane, pentane, hexane and heptane; saturatedcycloaliphatic hydrocarbons such as cyclopentane and cyclohexane;monoolefins such as 1-butene and 2-butene; aromatic hydrocarbons such asbenzene and toluene; halogenated hydrocarbons such as methylenechloride, chloroform, carbon tetrachloride, trichloroethylene,perchloroethylene, 1,2-dichloroethane, chlorobenzene, bromobenzene andchlorotoluene. Among them, toluene is preferred. Two or more solventsmay be used in combination.

Polymerization temperature in the polymerization method of the presentinvention may be, for example, in the range of from −100° C. to 100° C.preferably in the range of from −50° C. to 80° C. Polymerization timemay be, for example, about 1 minute to 12 hours, preferably about 5minutes to 5 hours. However, these reaction conditions may be suitablyselected depending on the type of monomers and the type of the catalystcomposition, and they are not limited to the ranges exemplified above.After the polymerization reaction reaches to a given polymerizationdegree, the reaction may be stopped by adding a known polymerizationterminator to the polymerization system, and then a produced polymer maybe separated from the reaction system in a conventional manner.

The content of the cis-configuration in the microstructure of thepolymer obtained by the polymerization method for a conjugated diene ofthe present invention may generally be 80 mol % or more, preferably 90mol % or more, more preferably 95 mol % or more, and most preferably 98mol % or more. As for the molecular weight distribution, Mw/Mn may be2.00 or less, preferably 1.80 or less, more preferably 1.60 or less,further preferably. 1.40 or less, and most preferably 1.30 or less.

The content of the cis-configuration in the microstructure of thecopolymer obtained by the copolymerization method of the presentinvention may generally be 80 mol % or more, preferably 90 mol % ormore, and most preferably 95 mol % or more. The molecular weight Mn maybe 10,000 or more, preferably 20,000 or more, more preferably 50,000 ormore, and most preferably 100,000 or more, and the molecular weightdistribution Mw/Mn may be 2.50 or less, preferably 2.00 or less, morepreferably 1.80 or less, and most preferably 1.50 or less. The copolymerof the present invention is a random copolymer that shows asubstantially randomized monomer sequence.

The polymers of present invention are expected to have superior thermalcharacteristics (thermal stability and the like) and mechanicalproperties (tensile modulus, bending modulus and the like), andtherefore, they can be utilized for various applications as polymericmaterials.

EXAMPLES

The present invention will be explained more specifically with referenceto the following examples. However, the scope of the present inventionis not limited to these examples.

Microstructures of polybutadiene referred to in the examples werecalculated from integration ratios of peaks observed by ¹H NMR and ¹³CNMR [¹H NMR: δ 4.8-5.0 (═CH₂ of 1,2-vinyl unit), 5.2-5.8 (—CH═ of1,4-unit and —CH═ of 1,2-vinyl unit), —C NMR: δ 27.4 (1,4-cis unit),32.7 (1,4-trans unit), 127.7-131.8 (1,4-unit), 113.8-114.8 and143.3-144.7 (1,2-vinyl unit)]. Styrene contents referred to in theexamples were calculated from integration ratios of the peaks obtainedby ¹H NMR [δ 4.8-5.0 (═CH₂ of 1,2-vinyl unit in butadiene), δ 5.2-5.8(—CH═ of 1,4-vinyl unit and 1,2-vinyl unit in butadiene) and δ 6.3-7.3(aromatic ring of styrene unit)]. The weight average molecular weights(Mw), number average molecular weights (Mn) and molecular weightdistributions (Mw/Mn) were obtained by gel permeation chromatographyusing polystyrene as a standard substance.

Example 1

In a glove box under nitrogen atmosphere, 0.01 mmol ofbispentamethylcyclopentadienylbistetrahydrofuran samarium[(Cp*)₂Sm(THF)₂] (Cp*:pentamethylcyclopentadienyl ligand)] was put intoa sufficiently dried 30-ml pressure glass bottle, and dissolved in 6 mlof toluene. Then, MMAO (toluene-soluble aluminoxane sold by TOSOH andAkzo Co.) was added into the bottle so that the elemental ratio of Al/Smbecame 200, and the bottle was sealed with a stopper. The bottle wasthen taken out from the glove box, and 1.5 g of 1,3-butadiene was putinto the bottle, and then polymerization was carried out for 5 minutesat 50° C. After the polymerization, 10 ml of methanol containing 10 wt %BHT [2,6-bis(tert-butyl)-4-methylphenol] was added to the reactionsystem to stop the reaction. The polymer was separated by using a largeramount of a mixed solvent of methanol/hydrochloric acid, and dried at60° C. in vacuo. The yield of the resulting polymer was 65 wt %. Thecis-content in the microstructure of the polymer was 98.8 mol %. Thenumber average molecular weight was 401,000 and Mw/Mn was 1.82.

Example 2

In a glove box under nitrogen atmosphere, 0.01 mmol ofmethylbispentamethylcyclopentadienyltetrahydrofuran samarium[(Cp*)₂SmMe(THF)] was put into a sufficiently dried 30-ml pressure glassbottle, and dissolved in 6 ml of toluene. Then, MMAO was added into thebottle so that the elemental ratio Al/Sm became 200, and the bottle wassealed with a stopper. The bottle was then taken out from the glove boxand 1.5 g of 1,3-butadiene was put into the bottle, and polymerizationwas carried out at 50° C. for 15 minutes. After the polymerization, 10ml of methanol containing 10 wt % BHT was added to the reaction systemto stop the reaction. The polymer was separated by using a larger amountof a mixed solvent of methanol/hydrochloric acid, and dried at 60° C. invacuo. The yield of the resulting polymer was 86 wt %. The cis-contentin the microstructure of the polymer was 98.0 mol %. The number averagemolecular weight was 1,260,000 and Mw/Mn was 1.82.

Example 3

In a glove box under nitrogen atmosphere, 0.01 mmol ofbispentamethylcyclopentadienylbistetrahydrofuran samarium[(Cp*)₂Sm(THF)₂] was put into a sufficiently dried 30-ml pressure glassbottle, and dissolved in 6 ml of toluene. Then, 0.1 mmol oftriisobutylaluminum and 0.01 mmol of triphenylcarboniumtetrakis(pentafluorophenyl)borate (Ph₃CB (C₆F₅)₄) were added into thebottle, and the bottle was sealed with a stopper. The bottle was thentaken out from the glove box and 1.5 g of 1,3-butadiene was put into thebottle, and polymerization was carried out at 50° C. for 10 minutes.After the polymerization, 10 ml of methanol containing 10 wt % BHT wasadded to the reaction system to stop the reaction. The polymer wasseparated by using a larger amount of a mixed solvent ofmethanol/hydrochloric acid, and dried at 60° C. in vacuo. The yield ofthe resulting polymer was 78 wt %. The cis-content in the microstructureof the polymer was 95.0 mol %. The number average molecular weight was263,000 and Mw/Mn was 1.34.

Example 4

In a glove box under nitrogen atmosphere, 0.01 mmol ofdimethylaluminum-(μ-dimethyl)bis(pentamethylcyclopentadienyl) samarium[(Cp*)₂Sm(μ-Me)₂AlMe₂] was put into a sufficiently dried 30-ml pressureglass bottle, and dissolved in 6 ml of toluene. Then, 0.03 mmol oftriisobutylaluminum and 0.01 mmol of triphenyl-carboniumtetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) were added into thebottle, and the bottle was sealed with a stopper. The bottle was thentaken out from the glove box and 1.5 g of 1,3-butadiene was put into thebottle, and polymerization was carried out at 50° C. for 5 minutes.After the polymerization, 10 ml of methanol containing 10 wt % BHT wasadded to the reaction system to stop the reaction. The polymer wasseparated by using a larger amount of a mixed solvent ofmethanol/hydrochloric acid, and dried at 60° C. in vacuo. The yield ofthe resulting polymer was 94 wt %. The cis-content in the microstructureof the polymer was 90.0 mol %. The number average molecular weight was429,500 and Mw/Mn was 1.56.

Example 5

In a glove-box under nitrogen atmosphere, 0.03 mmol ofdimethylaluminum-(μ-dimethyl)bis(pentamethylcyclopentadienyl) samarium[(Cp*)₂Sm(μ-Me)₂AlMe₂] (Cp*:pentamethylcyclopentadienyl ligand) was putinto a sufficiently dried 30-ml pressure glass bottle, and dissolved in1 ml of toluene. Then, 0.09 mmol of triisobutylaluminum and 0.03 mmol oftriphenylcarbonium tetrakis (pentafluoro-phenyl)borate (Ph₃CB(C₆F₅)₄)were added into the bottle, and the bottle was sealed with a stopper.The bottle was then taken out from the glove box and 0.97 g of1,3-butadiene and 1.4 ml of styrene were put into the bottle, andpolymerization was carried out at 50° C. for 30 minutes. After thepolymerization, 10 ml of methanol containing 10 wt % BHT[2,6-bis(tert-butyl)-4-methylphenol] was added to the reaction system tostop the reaction. The polymer was separated by using a larger amount ofa mixed solvent of methanol/hydrochloric acid, and dried at 60° C. invacuo. The yield of the resulting polymer was 21 wt %. The styrenecontent in the polymer was 4.6 mol % and the cis-content in themicrostructure of the butadiene units was 94.6 mol %. The number averagemolecular weight was 101,000 and Mw/Mn was 1.41.

Example 6

A polymer was obtained in the same manner as in Example 5 except that0.81 g of 1,3-butadiene and 1.7 ml of styrene were used, andpolymerization was carried out at 50° C. for 1 hour. The yield of theresulting polymer was 22 wt %. The styrene content in the polymer was7.2 mol % and the cis-content in the microstructure of the butadieneunits was 95.1 mol %. The number average molecular weight was 78,600 andMw/Mn was 1.59.

Example 7

A polymer was obtained in the same manner as in Example 5 except that0.65 g of 1,3-butadiene and 2.0 ml of styrene were used, andpolymerization was carried out at 50° C. for 6 hours. The yield of theresulting polymer was 20 wt %. The styrene content in the polymer was11.4 mol % and the cis-content in the microstructure of the butadieneunits was 91.7 mol %. The number average molecular weight was 73,900 andMw/Mn was 1.69.

Example 8

A polymer was obtained in the same manner as in Example 5 except that0.49 g of 1,3-butadiene and 2.4 ml of styrene were used, andpolymerization was carried out at 50° C. for 12 hours. The yield of theresulting polymer was 23 wt %. The styrene content in the polymer was19.1 mol % and the cis-content in the microstructure of the butadieneunits was 87.4 mol %. The number average molecular weight was 38,700 andMw/Mn was 1.75.

Example 9

A polymer was obtained in the same manner as in Example 5 except that0.32 g of 1,3-butadiene and 2.8 ml of styrene were used, andpolymerization was carried out at 50° C. for 50 hours. The yield of theresulting polymer was 21 wt %. The styrene content in the polymer was33.2 mol % and the cis-content in the micrustructure of the butadieneunits was 80.3 mol %. The number average molecular weight was 23,400 andMw/Mn was 2.23.

The results of Examples 5 to 9 are summarized in the following Table 1.

TABLE 1 Amount of Microstructure St used Polymerization Yield 1,4-cis1,4-trans 1,2- St content (mol %) time (h) (%) (%) (%) (%) (%) Mw MnMw/Mn 40 0.5 21 94.6 4.4 1.0 4.6 142,000 101,000 1.41 50 1 22 95.1 3.91.0 7.2 124,800 78,600 1.59 60 6 20 91.7 7.2 1.1 11.4 124,200 73,9001.69 70 12 23 87.4 11.7 0.9 19.1 67,800 38,700 1.75 80 50 21 80.3 18.71.0 33.2 52,200 23,400 2.23

INDUSTRIAL AVAILABILITY

By polymerizing a conjugated diene using the catalyst composition ofpresent invention, a polymer can be obtained which has an extremely highcontent of cis-1,4-configuration in the microstructure and a narrowmolecular weight distribution. Further, by using the catalystcomposition of present invention, a random copolymer can be obtainedusing a conjugated diene and an aromatic vinyl compound which has a highcontent of cis-1,4-configuration in the microstructure, a high molecularweight, and a narrow molecular weight distribution.

What is claimed is:
 1. A copolymer which is obtainable bycopolymerization of a conjugated diene and an aromatic vinyl compound inthe presence of a catalyst composition comprising: (A) a metallocenecomplex of a rare earth metal compound, and (B) an ionic compoundcomposed of a non-coordinate anion and cation and/or an aluminoxane,wherein said copolymer has a cis-1,4-configuration content in itsmicrostructure of 80 mol % or more and a molecular weight distributionMw/Mn of 2.50 or less.
 2. The copolymer according to claim 1, wherein acis-1,4-configuration content in the microstructure is 80 mol % or moreand a molecular weight distribution Mw/Mn is 2.00 or less.
 3. A randomcopolymer of a conjugated diene and an aromatic vinyl compound, whereina cis-1,4-configuration content in the microstructure is 80 mol % ormore, a molecular weight Mn is 10,000 or more, and a molecular weightdistribution Mw/Mn is 2.50 or less.
 4. A copolymer which is obtained bycopolymerization of a conjugated diene and an aromatic vinyl compound inthe presence of a catalyst composition comprising: (A) a metallocenecomplex of a rare earth metal compound, and (B) an ionic compoundcomposed of a non-coordinate anion and cation and/or an aluminoxane,wherein said copolymer has a cis-1,4-configuration content in itsmicrostructure 80 mol % or more and a molecular weight distributionMw/Mn of 2.50 or less.
 5. A random copolymer of a conjugated diene andan aromatic vinyl compound, having a cis-1,4-configuration content inthe microstructure of 80 mol % or more and a molecular weightdistribution Mw/Mn of 2.50 or less.
 6. The copolymer according to claim3, wherein the cis-1,4-configuration content in the microstructure is 80mol % or more and the molecular weight distribution Mw/Mn is 2.00 orless.